Ethylene-based polymers have been employed in manufacturing film products, such as blown films used in garbage bags. An ethylene-based polymer commonly employed in such blown films is linear low density polyethylene (LLDPE), a semi-crystalline polymer. LLDPE films provide good toughness, puncture resistance, and drop strength, which are important properties for garbage bags.
A conventional means of improving the toughness of a semi-crystalline linear ethylene polymer is to introduce an additive polymer having short- or long-chain branching. Introduction of a branched polymer is known to raise the inter-crystalline connectivity, or so called the tie chain concentration, leading to the enhancement in linear ethylene polymer toughness and strength. High molecular weight linear ethylene polymers contribute to tie chain development as a result of their inability to relax and retract their long chains during the formation of chain-folded crystallites. Short and long-chain branches contribute to tie chain formation since the branches cannot be incorporated into crystallites.
Conventional low density polyethylene (LDPE) typically exhibits a significant degree of short- and/or long-chain branching. LDPE is frequently blended with linear ethylene polymers, such as LLDPE, to enhance resin processability. However, addition of LDPE has the negative effect of reducing the strength and toughness of blends containing LLDPE.
It would be desirable to have a branched ethylene polymer that can be added to a matrix linear ethylene polymer to enhance toughness without diminishing strength. It would be further desirable to have a branched ethylene polymer that can be added to LLDPE to enhance toughness without diminishing strength and processability.